The present disclosure relates to a method and a system for applying a coating material onto components of work pieces to be processed in series, e.g., in accordance with the preamble of the independent patent claims, for example for the application of a sealing material onto doors, bonnets or other attachment parts of vehicle bodies. In particular, it may be the application of paths to seal areas, such as e.g. flanged folds, of the attachment parts, which are not visible from the outside when the attachment part is in its closed position in or on the work piece.
To increase the degree of automation in the coating of work pieces, such as vehicle bodies, robots are to be increasingly used also for coating operations, which so far could only be performed manually. One example for such processes is the sealing of joints or folds on parts of the body, which are later visible on the finished vehicle by its user and for which high demands are thus placed not only on the sealing function but also on the optical appearance.
In this connection, however, the problem arises that a part of these sealing processes has to be performed on vehicle areas, which are not accessible without any problems. This includes, for example, the sealing of flanged folds on vehicle doors. These folds are on the inner surface of the doors and are to be coated in a serial operation while the doors are closed to avoid the additional effort of opening and closing the door in the course of this. Thus, the programming should also not take place while the door is open. This results in the programming of the application paths being very laborious and difficult as the programmer cannot see the exact position of the application nozzle in relation to the surface area to be coated when tracking the flanged seam invisible on the inner surface of the closed door. It virtually has to be programmed “blindly”.
To apply a sealant to a flanged seam of closed doors or other attachment parts of vehicle bodies, various application tools and corresponding methods are generally known.
One possibility to simplify the programming process would be the so-called off-line programming on a computer independent from the robot. In this connection, a movement path of the robot can be generated on the computer on the basis of existing data of the respective vehicle part and the robot cell and can optionally be combined with the required application parameters. These programs can then be transmitted to the robot, which can perform the application after a corresponding initial measurement of the work piece. However, in the application of sealing paths, this procedure has the problem of tolerance chains, for example where the use of the robot and the independent computer result in additions of tolerances for both machines and/or other devices. The additive tolerances may be too large in many cases, and may result in difficulties fulfilling appearance requirements or demands for the optical appearance of the seal joint. In the worst case, undesired collisions between the applicator or the application nozzle and the component to be coated also result. Subsequent teaching of the entire application work flow is then required.
As a result, in practice the programming can currently only be performed iteratively: after a first programming, the application initially takes place by way of trial and the application pattern is examined after opening the attachment part to be coated. It is attempted to draw conclusions from the optical appearance of the application with regard to the parameters to be optimized, which can be both motion parameters of the robot and application parameters. On this basis, corresponding modifications to the application program are made and another application is performed with the component being closed. The next iteration step takes place thereafter. The iteration method is continued until the application is satisfactory. This method is undesirably labour-intensive and time-consuming. This method may be particularly time-consuming and/or labor-intensive where components being coated or worked upon are installed to enclosures, e.g., vehicle bodies, that limit access to the component.
Accordingly, there is a need for an improved method and system, e.g., of the type mentioned at the outset, which, in comparison to the prior art, allow for a substantially simpler and more precise programming of the robot for the coating of component areas, which are not visible from the outside during the normal serial coating process.